1. Field of the Invention
The present invention relates generally to document authenticity and, more particularly, to verifying the date a document was created or existed.
2. Description of Related Art
Document management is very important in electronic commerce applications. For instance, a digital watermark may be employed to embed information into a digital file. This information may be used to deter unauthorized copying of the digital file. Content restrictions may be added to digital media such as music or movies to limit the number of legal copies which can be made. Furthermore, a digital file may be encrypted for security purposes as part of content distribution.
While such processes may deter theft or unauthorized copying, they do not provide a mechanism to prove to a third party when a particular piece of content was created or modified.